Bradley Johnston, in his book "150 Questions about the Psalter", quotes from William Binnie to answer the question posed in our title.
Question 140:
How should the majesty and ancient authority of the Psalter mold worship services?
Answer 140:
"In the Church of Jesus Christ, where the prayers are free, it is of utmost importance that services of worship should be molded in the forms of ancient authority; and surely the best possible mold is that which the Holy Spirit Himself gave by the Psalmists, which has left its divinely guided lines on the Church for these three thousand years."
I'm struck by that phrase, "divinely guided lines", and the compelling suggestion that this is the mold that we are to see impressed upon our services of divine worship. As I continue to grow in my understanding of and appreciation for the Psalms, I'm amazed at the ways in which the indelible mark of the Holy Spirit's inspiration becomes more and more evident in these sacred compositions.
What do we currently have in our repertoire that bears the majesty and ancient authority of Holy Scripture?